1. Field of the Invention
The invention relates to a trocar for use during deployment of an anastomosis device and a method of per anastomosis. In a preferred embodiment, the trocar can be used for piercing vessel wall as an initial step in forming a sutureless connection between a bypass graft and a blood vessel.
2. Brief Description of the Related Art
Vascular anastomosis is a procedure by which two blood vessels within a patient are surgically joined together. Vascular anastomosis is performed during treatment of a variety of conditions including coronary artery disease, diseases of the great and peripheral vessels, organ transplantation, and trauma. In coronary artery disease (CAD) an occlusion or stenosis in a coronary artery interferes with blood flow to the heart muscle. Treatment of CAD involves the grafting of a vessel in the form of a prosthesis or harvested artery or vein to reroute blood flow around the occlusion and restore adequate blood flow to the heart muscle. This treatment is known as coronary artery bypass grafting (CABG).
In the conventional CABG, a large incision is made in the chest and the sternum is sawed in half to allow access to the heart. In addition, a heart lung machine is used to circulate the patients blood so that the heart can be stopped and the anastomosis can be performed. During this procedure, the aorta is clamped which can lead to trauma of the aortic tissue and/or dislodge plaque emboli, both of which increase the likelihood of neurological complications. In order to minimize the trauma to the patient induced by conventional CABG, less invasive techniques have been developed in which the surgery is performed through small incisions in the patients chest with the aid of visualizing scopes. Less invasive CABG can be performed on a beating or stopped heart and thus may avoid the need for cardiopulmonary bypass.
In both conventional and less invasive CABG procedures, the surgeon has to suture one end of the graft vessel to the coronary artery and the other end of the graft vessel to a blood supplying vein or artery. The suturing process is a time consuming and difficult procedure requiring a high level of surgical skill. In order to perform the suturing of the graft to the coronary artery and the blood supplying artery the surgeon must have relatively unobstructed access to the anastomosis site within the patient. In the less invasive surgical approaches, some of the major coronary arteries including the ascending aorta cannot be easily reached by the surgeon because of their location. This makes suturing either difficult or impossible for some coronary artery sites. In addition, some target vessels, such as heavily calcified coronary vessels, vessels having very small diameter, and previously bypassed vessels may make the suturing process difficult or impossible.
An additional problem with CABG is the formation of thrombi and atherosclerotic lesions at and around the grafted artery, which can result in the reoccurrence of ischemia. The thrombi and atherosclerotic lesions may be caused by the configuration of the sutured anastomosis site. For example, an abrupt edge at the anastomosis site may cause more stenosis than a more gradual transition.
Accordingly, it would be desirable to provide a sutureless vascular anastomosis device which easily connects a graft to a target vessel. It would also be desirable to provide a sutureless anastomosis device which is formed of one piece and is secured to the target vessel in a single step.
According to a preferred embodiment, the present invention relates to a trocar for forming an incision in a wall of a target vessel such as an aorta and a deployment tool for delivering an anastomosis device for connecting the end of a graft vessel to a target vessel at the site of the incision. The trocar comprises a member such as a tubular member having a piercing element and the member being adapted to cooperate with a deployment tool such that the anastomosis device can be delivered by the deployment tool and the trocar can be withdrawn from the incision site prior to deployment of the anastomosis device.
The trocar can include various features. For instance, the piercing element can comprise a cutting blade which is movable with respect to the tubular member such that the cutting blade can be moved from a cutting position at which the cutting blade is exposed to a retracted position at which the cutting blade is not exposed. Likewise, the piercing element can comprise a sharpened inclined surface at the distal end of the tubular member. The tubular member can also include distal and proximal portions where the distal portion has a smaller diameter than the proximal portion, and the inclined surface is located on a free end of the distal portion. In addition, the distal portion can include at least one axially extending tear line which allows the distal portion to be split and expanded over the anastomosis device.
According to another embodiment of the invention, the tubular member of the trocar can include a deformable tubular wall. The tubular wall can include openings therein which allow the tubular member to be deformed from a smaller configuration to a larger configuration. The openings can include a plurality of axially extending wall sections and a plurality of circumferentially extending wall sections. The inclined surface can be a continuous surface interrupted by a plurality of slits extending between the inclined surface and the openings closest to the inclined surface. The openings can also include axially extending slots arranged in a staggered pattern such that the circumferentially extending wall sections intersect a pair of slots.
According to another embodiment of the invention, the piercing element can include a vessel wall piercing portion and trimming portion. The piercing portion forms the incision upon insertion of the distal end of the tubular member into the vessel wall and the trimming portion removes tissue around the incision upon retraction of the tubular member. The piercing element can also include a plurality of axially extending tines at the distal end of the tubular member. In this manner, the trimming portion is formed as the cutting edges on outer surfaces of the tines, which remove the tissue upon retraction from the tubular member.
According to another embodiment of the invention, the piercing element can include a cutting blade which forms an elongated slit upon insertion of the piercing element into the vessel wall. The tubular member can include tines at the distal end thereof, the tines being separated from each other and from the cutting blade by axially extending slits. The distal ends of the tines can be biased in close proximity to each other at a location spaced from the distal end of the cutting blade. The cutting blade can include two cutting edges which meet at a point and form an angle therebetween. The piercing element can also comprise a flat pointed blade sized to provide the incision with a size smaller than the anastomosis device in an expanded condition.
In accordance with an additional aspect of the present invention, a method of performing anastomosis includes the step of using a trocar to form an incision in a wall of a target vessel such as an aorta. The anastomosis device is then inserted into the incision through the trocar. The first portion is manipulated with respect to a second portion of the anastomosis device to capture edges of the incision in the target vessel with the anastomosis device such that a fluid passage is established between the graft vessel and the target vessel.
Preferably, the target vessel is an aorta and the method is performed without occlusion (i.e., clamping) of the aorta. The end of the graft vessel and the edges of the incision in the target vessel can be captured between the first portion and the second portion so that the end of the graft vessel abuts an outside wall of the target vessel. The anastomosis device can be expandable from a first configuration to a larger second configuration where the anastomosis device is expanded with an expander to cause a portion of the anastomosis device to fold outward forming the first flange. In this regard, the first flange holds a portion of the graft vessel in contact with an inner surface of the target vessel.
The method can also include the step of retracting the trocar over the anastomosis device and along the expander prior to expanding the anastomosis device with the expander where the trocar is deformed during the retracting step. Preferably, the second flange can be formed by axially compressing the anastomosis device with a deployment tool. The deployment tool can comprise a tube which engages a proximal end of the anastomosis device where the compression step is carried out by withdrawing the expander through the tube. A groove on the expander can engage tabs on the anastomosis device during formation of the second flange.
According to another aspect of the invention, the anastomosis device can be severed into a deployed portion and a discard portion during the step of forming the second flange. The anastomosis device can comprise an expandable linkage which is delivered through the trocar to the site of the incision, the linkage being deformed to an expanded size during formation of the first and second flanges, the incision formed by the trocar being smaller than the expanded size. Finally, the first and second flanges can form an angle between 40 and 140 degrees with an axis of the anastomosis device.